The present invention is drawn to pre-filled syringes and, more particularly, an elastic-sliding valve to produce a hermetic closure inside a pre-filled syringe which keeps the liquid content to be injected totally isolated, in order to prohibit the liquid from coming in contact with the needle or the external air.
The characteristic feature of known pre-filled syringes is that they have a cylindrical and hollow main body, with a front section where a communication neck with the injection needle is formed, while inside is a manually movable plunger which extends outward from the back of the main body which is open. All of these known syringes have an inner chamber formed inside the main body, constituting the temporary location of the liquid to be injected. This inner chamber is defined by the cylindrical wall of the main body, the above mentioned front neck where the needle and the active head of the manually movable plunger.
Argentine Patent No. 250.277 discloses a syringe which supports a very special valve plug whose function is to keep the liquid isolated inside of syringe body thus avoiding contact with the needle until the injection is performed. Thus, during the placement of the needle and coupling it to the plugging cone or syringe neck and withdrawal of the protecting sheath to perform the injection, the liquid is kept isolated inside the main body of the syringe, ensuring that these coupling and uncoupling actions do not cause some unwanted loss or spilling. The plug is specially designed to be placed in the neck occluding the same from the outlet mouth. It is important to point out that the plug of the mentioned Patent No. 250.277 is specially designed for the mouth of the syringe neck that faces the injection needle. Due to its special shape the same releases the liquid only when hydraulic pressure is produced from the plunger towards the syringe. This pressure partially removes the plug and the liquid flows.
Accordingly, it would be highly desirable to provide a pre-filled syringe with an elastic-sliding valve which can be selectively located within the syringe so as to be operative with either a single product chamber or, alternatively, a first product chamber and a second product chamber wherein movement of the plunger away from the base opens the elastic-sliding valve member so as to mix the first product and the second product prior to dispensing same.
Accordingly, it is a principal object of the present invention to provide a pre-filled syringe as described above having an elastic-sliding valve selectively located in the syringe for dispensing either a single medicament product or delivering a plurality of medicament products which are mixed together prior to dispensing.
The elastic-sliding valve of the present invention is specifically designed to isolate the liquid contained in a pre-filled syringe, avoiding its contact with the needle; preferably, the elastic-sliding valve is located within the syringe so as to be effective for dispensing a single medicament product and, alternatively mixing a plurality of medicament products prior to dispensing.
The elastic-sliding valve comprises a discoidal elastic valve member and a cooperative element wherein one of the discoidal elastic valve member and cooperative element is movable relative to the other for opening the elastic-sliding valve for communicating product from an internal chamber of the pre-filled syringe upon movement of the plunger of the syringe toward the base of the syringe. In accordance with a preferred embodiment of the present invention, the discoidal elastic valve member has a peripheral portion which seals on the cylindrical wall and a disklike central portion. The cooperative element likewise comprises a peripheral portion for sealing on the cylindrical wall and includes a central portion. One of the central portions includes a closure element and the other of the central portion includes a fluid passage which receives the closure element when the elastic-sliding valve is in the closed position. In accordance with the preferred embodiment, the central portion of the discoidal elastic valve member is provided with the closure element and the central portion of the discoidal valve element further includes a plurality of openings distributed around the closure element for communicating product. The elastic-sliding valve may be located adjacent to the base of the syringe and in that position is useful for dispensing a single medicament product when the elastic-sliding valve is opened upon movement of the plunger away from the base and product is dispensed through the open valve upon forward movement of the plunger toward the base. Alternatively, the elastic-sliding valve divides the internal chamber into a first product chamber and a second product chamber. Movement of the plunger away from the base results in the opening of the elastic-sliding valve member so as to mix the product in the first chamber with the product in the second chamber prior to feeding the product upon movement of the plunger forward toward the base.